1. Field of the Invention
This invention relates to a vacuum brazing or soldering apparatus in which articles provided or clad with soldering or brazing material are heated and brazed with each other in a vacuum chamber.
2. Description of the Prior Art
In a prior vacuum brazing or soldering apparatus, a heating system consisting of a heater, electrodes, insulators, etc., and a reflector for reflecting heat from the heater and thermally shielding are arranged inside of a vacuum chamber. Articles provided with brazing material are heated by the heat from the heater and the radiant heat from the reflector, and so they are brazed or soldered to each other. The surface area of the inside wall of the vacuum chamber is large, and the whole of the vacuum chamber is large-sized. Further, the heating system functions as a gas-emitting source. Accordingly, it requires long time to vacuumize the vacuum chamber.
Further, in the prior vacuum brazing apparatus, while the inside wall of the vacuum chamber is thermally insulated by the reflector, the outside wall of the vacuum chamber is cooled with water. For example, the temperatures of the electrodes, inside wall of the vacuum chamber and back side of the reflector adjacent to the inside wall of the vacuum chamber become relatively low. Accordingly, various gases, oil, evaporating metal elements emitted from the articles to be brazed, adhere onto the electrodes, the inside wall of the vacuum chamber and the back side of the reflector. There occur the problems that the amount of the emitting gas increases on vaccumizing the vacuum chamber and that the electrical insulating parts are deteriorated. In order to solve the above problems, the inside of the vacuum chamber should be periodically cleaned. In the cleaning operation, the heating system should be decomposited. One cleaning operation requires usually about three weeks. The cleaning operation should be effected usually once or twice a year. The working efficiency of the apparatus is low.